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Margarella Expansa
''Margarella expansa'' is a species of sea snail, a marine gastropod mollusk in the family Calliostomatidae.Bouchet, P.; Rosenberg, G. (2012). ''Margarella expansa''. Accessed through: World Register of Marine Species at http://www.marinespecies.org/aphia.php?p=taxdetails&id=533026 on 2012-12-07 Description The shell grows to a height of 14.1 mm. The thin, imperforate shell has a depressed-conoidal shape. It is shining, of a light olivaceous tint or somewhat tinged with pink. Its surface is smooth. The acute spire is conoidal. The sutures are slightly impressed. The shell contains about 42 rapidly widening whorls. The large body whorl is rounded at the periphery and a little impressed or margined below the suture. The large aperture is rounded and angular above, green and iridescent inside. The columellar margin is a little straightened. The umbilico-columellar tract is slightly excavated. [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
George Brettingham Sowerby I
George Brettingham Sowerby I (12 August 1788 – 26 July 1854) was a British naturalist, illustrator and conchologist. Life He was the second son of James Sowerby. George was educated at home under private tutors, and afterwards assisted his father in the production of illustrated works on natural history. On the latter's death in 1822, he and his brother James De Carle Sowerby continued their father's work on fossil shells, publishing the latter parts of the ''Mineral Conchology of Great Britain''. He published about 50 papers on molluscs and started several comprehensive, illustrated books on the subject, the most important the ''Thesaurus Conchyliorum'', a work that was continued by his son, George Brettingham Sowerby II and his grandson George Brettingham Sowerby III. One of his first works was the cataloguing of the collection of the Earl of Tankerville. He also dealt in shells and natural history objects, his place of business being first in King Street, Covent Garden, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Suture (anatomy)
In anatomy, a suture is a fairly rigid joint between two or more hard elements of an organism, with or without significant overlap of the elements. Sutures are found in the skeletons or exoskeletons of a wide range of animals, in both invertebrates and vertebrates. Sutures are found in animals with hard parts from the Cambrian period to the present day. Sutures were and are formed by several different methods, and they exist between hard parts that are made from several different materials. Vertebrate skeletons The skeletons of vertebrate animals (fish, amphibians, reptiles, birds, and mammals) are made of bone, in which the main rigid ingredient is calcium phosphate. Cranial sutures The skulls of most vertebrates consist of sets of bony plates held together by cranial sutures. These sutures are held together mainly by Sharpey's fibers which grow from each bone into the adjoining one. Sutures in the ankles of land vertebrates In the type of crurotarsal ankle which is found ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Straits Of Magellan
The Strait of Magellan (), also called the Straits of Magellan, is a navigable sea route in southern Chile separating mainland South America to the north and Tierra del Fuego to the south. The strait is considered the most important natural passage between the Atlantic and Pacific oceans. It was discovered and first traversed by the Spanish expedition of Ferdinand Magellan in 1520, after whom it is named. Prior to this, the strait had been navigated by canoe-faring indigenous peoples including the Kawésqar. Magellan's original name for the strait was ''Estrecho de Todos los Santos'' ("Strait of All Saints"). The King of Spain, Emperor Charles V, who sponsored the Magellan-Elcano expedition, changed the name to the Strait of Magellan in honor of Magellan. The route is difficult to navigate due to frequent narrows and unpredictable winds and currents. Maritime piloting is now compulsory. The strait is shorter and more sheltered than the Drake Passage, the often stormy open sea ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Falkland Islands
The Falkland Islands (; es, Islas Malvinas, link=no ) is an archipelago in the South Atlantic Ocean on the Patagonian Shelf. The principal islands are about east of South America's southern Patagonian coast and about from Cape Dubouzet at the northern tip of the Antarctic Peninsula, at a latitude of about 52°S. The archipelago, with an area of , comprises East Falkland, West Falkland, and 776 smaller islands. As a British overseas territory, the Falklands have internal self-governance, but the United Kingdom takes responsibility for their defence and foreign affairs. The capital and largest settlement is Stanley on East Falkland. Controversy exists over the Falklands' discovery and subsequent colonisation by Europeans. At various times, the islands have had French, British, Spanish, and Argentine settlements. Britain reasserted its rule in 1833, but Argentina maintains its claim to the islands. In April 1982, Argentine military forces invaded the islands. British a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Columella (gastropod)
The columella (meaning "little column") or (in older texts) pillar is a central anatomical feature of a coiled snail shell, a gastropod shell. The columella is often only clearly visible as a structure when the shell is broken, sliced in half vertically, or viewed as an X-ray image. The columella runs from the apex of the shell to the midpoint of the undersurface of the shell, or the tip of the siphonal canal in those shells which have a siphonal canal. If a snail shell is visualized as a cone of shelly material which is wrapped around a central axis, then the columella more or less coincides spatially with the central axis of the shell. In the case of shells that have an umbilicus, the columella is a hollow structure. The columella of some groups of gastropod shells can have a number of plications or folds (the columellar fold, plaits or plicae), which are usually visible when looking to the inner lip into the aperture of the shell. These folds can be wide or narrow, prominent ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Aperture (mollusc)
The aperture is an opening in certain kinds of mollusc shells: it is the main opening of the shell, where the head-foot part of the body of the animal emerges for locomotion, feeding, etc. The term ''aperture'' is used for the main opening in gastropod shells, scaphopod shells, and also for ''Nautilus'' and ammonite shells. The word is not used to describe bivalve shells, where a natural opening between the two shell valves in the closed position is usually called a ''gape''. Scaphopod shells are tubular, and thus they have two openings: a main anterior aperture and a smaller posterior aperture. As well as the aperture, some gastropod shells have additional openings in their shells for respiration; this is the case in some Fissurellidae (keyhole limpets) where the central smaller opening at the apex of the shell is called an orifice, and in the Haliotidae (abalones) where the row of respiratory openings in the shell are also called orifices. In gastropods In some prosobranch ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Body Whorl
The body whorl is part of the morphology of the shell in those gastropod mollusks that possess a coiled shell. The term is also sometimes used in a similar way to describe the shell of a cephalopod mollusk. In gastropods In gastropods, the body whorl, or last whorl, is the most recently formed and largest whorl (or revolution) of a spiral or helical shell, terminating in the aperture. It is called the "body whorl" because most of the body of the soft parts of the animal fits into this whorl. The proportional size of the body whorl in gastropod shells differs greatly according to the actual shell morphology. For shells in which the rate of whorl expansion of each revolution around the axis is very high, the aperture and the body whorl are large, and the shell tends to be low spired. The shell of the abalone is a good example of this kind of shell. The opposite tendency can sometimes create a high spire with very little whorl increase per revolution. In these instances, e.g. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Whorl (mollusc)
A whorl is a single, complete 360° revolution or turn in the spiral growth of a mollusc shell. A spiral configuration of the shell is found in numerous gastropods, but it is also found in shelled cephalopods including ''Nautilus'', ''Spirula'' and the large extinct subclass of cephalopods known as the ammonites. A spiral shell can be visualized as consisting of a long conical tube, the growth of which is coiled into an overall helical or planispiral shape, for reasons of both strength and compactness. The number of whorls which exist in an adult shell of a particular species depends on mathematical factors in the geometric growth, as described in D'Arcy Wentworth Thompson's classic 1917 book ''On Growth and Form'', and by David Raup. The main factor is how rapidly the conical tube expands (or flares-out) over time. When the rate of expansion is low, such that each subsequent whorl is not that much wider than the previous one, then the adult shell has numerous whorls. When the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Spire (mollusc)
A spire is a part of the coiled shell of molluscs. The spire consists of all of the whorls except for the body whorl. Each spire whorl represents a rotation of 360°. A spire is part of the shell of a snail, a gastropod mollusc, a gastropod shell, and also the whorls of the shell in ammonites, which are fossil shelled cephalopods. In textbook illustrations of gastropod shells, the tradition (with a few exceptions) is to show most shells with the spire uppermost on the page. The spire, when it is not damaged or eroded, includes the protoconch (also called the nuclear whorls or the larval shell), and most of the subsequent teleoconch whorls (also called the postnuclear whorls), which gradually increase in area as they are formed. Thus the spire in most gastropods is pointed, the tip being known as the "apex". The word "spire" is used, in an analogy to a church spire or rock spire, a high, thin, pinnacle. The "spire angle" is the angle, as seen from the apex, at which a spire ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Species
In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. Other ways of defining species include their karyotype, DNA sequence, morphology, behaviour or ecological niche. In addition, paleontologists use the concept of the chronospecies since fossil reproduction cannot be examined. The most recent rigorous estimate for the total number of species of eukaryotes is between 8 and 8.7 million. However, only about 14% of these had been described by 2011. All species (except viruses) are given a two-part name, a "binomial". The first part of a binomial is the genus to which the species belongs. The second part is called the specific name or the specific epithet (in botanical nomenclature, also sometimes i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
World Register Of Marine Species
The World Register of Marine Species (WoRMS) is a taxonomic database that aims to provide an authoritative and comprehensive list of names of marine organisms. Content The content of the registry is edited and maintained by scientific specialists on each group of organism. These taxonomists control the quality of the information, which is gathered from the primary scientific literature as well as from some external regional and taxon-specific databases. WoRMS maintains valid names of all marine organisms, but also provides information on synonyms and invalid names. It is an ongoing task to maintain the registry, since new species are constantly being discovered and described by scientists; in addition, the nomenclature and taxonomy of existing species is often corrected or changed as new research is constantly being published. Subsets of WoRMS content are made available, and can have separate badging and their own home/launch pages, as "subregisters", such as the ''World List of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Calliostomatidae
Calliostomatidae is a family of sea snails within the superfamily Trochoidea and the clade Vetigastropoda.Gofas, S. (2013). Calliostomatidae. Accessed through: World Register of Marine Species at http://www.marinespecies.org/aphia.php?p=taxdetails&id=382180 on 2013-07-08 Description The Calliostomatidae are unusually diverse. They are characterized by a stepped spire and a pointy aperture. They may possess or lack an umbilicus. The collumella is sometimes thicker, partially covering the aperture. The spiral whorls can differ between narrow and robust. They inhabit a wide range of ocean habitats, from the intertidal zone to mid- bathyal depths. Taxonomy This taxon was long considered to be a subfamily of the Trochidae. 2005 taxonomy This family consists of two following subfamilies (according to the taxonomy of the Gastropoda by Bouchet & Rocroi, 2005): * subfamily Calliostomatinae Thiele 1924 (1847) ** tribe Calliostomatini Thiele 1924 (1847) - synonym: Ziziphininae G ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
